Computer-aided design (CAD) refers to the use of computers to assist designers in the designing of a product. The designer uses a CAD system to identify the geometry and other critical characteristics of the product. Most conventional CAD systems create models of the products that capture the geometric characteristics of the product, such as the geometry of the product. Such models are provided in a number of different varieties. “Feature-based models” represent products as combinations of “features.” A “feature” is a set of data and procedures for generating shape or characteristic of a product that can be associated with certain attributes and knowledge about the product. In general, features serve as the building blocks for product modeling.
Some conventional CAD systems generate “parametric models.” Parametric models represent models as sets of procedures having input parameters such as dimension values and output geometry. A parametric model stores a procedure for constructing the computer model of a product. In parametric models, the procedure for constructing the product may be viewed as a sequence of assignments to model variables as a function of input parameters for parametric equations. To create parametric variations, the construction procedure is reevaluated after changing the values of the input parameters (such as dimension values). This general definition of “parametric models” includes “variational models” or “variable-driven models” generated by some conventional CAD systems.
As part of the design of a product, it is often necessary to perform analysis, such as engineering analysis, on the model of the product. Often, separate application programs are run to perform analysis on a product. The designer must then view the analysis and manually make appropriate changes to the model to obtain the desired analysis results. Some conventional CAD programs provide some analysis tools in the CAD package. In such cases, the analysis results are not integrated into the model but rather exist as separate data in the CAD package. As a result, it is often difficult for a designer to work with the model and the engineering analysis simultaneously.